In recent years, real time communications have widespread using means of VoIP (Voice over IP), TV phones, etc. in wireless system packet communication networks. Consequently, the traffics of such real time communications are now increasing more and more. On the other hand, as the functions of those wireless systems, such as QoS (Quality of Service) control, policy control, dynamic address assignment, authentication, etc. have been enhanced and complicated, the hand-over time have also been extended accordingly. Under such circumstances, keeping the real time communication quality even at such hand-over events is becoming one of the vital issues.
In a wireless system, a base station and a mobile station communicate wirelessly with each other in units of wireless sending information formed from such packets as those of the IP (Internet Protocol), etc. And in order to use its wireless resources efficiently by reducing occurrence of conflictions among information items to be sent and by reducing the wireless sending time, the wireless system schedules wireless packet sending by information units. For example, IEEE Std 802. 16e-2005, (Feb. 28, 2006)/IEEE Std 802. 16-2004/Cor1 6.3.5.2 discloses how a base station schedules data sending according to a band width request from a mobile station and its own necessary band width, as well as its procedure. IEEE Std 802. 16e-2005, (Feb. 28, 2006)/IEEE Std 802. 16-2004/Cor1 6.3.2.1.2.1.1 discloses message formats. IEEE Std 802. 16e-2005, (Feb. 28, 2006)/IEEE Std 802. 16-2004/Cor1 8.3.5.1 discloses wireless sending information formats.